Thermo formable acoustical panel

ABSTRACT

Disclosed is both a method and composition for forming a thermo-formable acoustical panel. The panel may be formed from multi-component polymer fibers or mono-filament polymer fibers dispersed in a mineral fiber batt. The polymer fibers are bound to the mineral fibers by the application of heat to form the acoustical panel. The panel exhibits both enhanced flame resistance and thermal insulation.

RELATED APPLICATION

[0001] This application is a continuation-in-part application claimingthe benefit of application Ser. No. 09/956,665, filed Sep. 20, 2000, thecontent of which is hereby incorporated in its entirety.

FIELD OF INVENTION

[0002] The present invention generally relates to acoustical panels andmore specifically to thermo formable acoustical panels.

BACKGROUND

[0003] Fibrous acoustical panels are used for a variety of differentpurposes and are comprised of an array of different fibers, binders andfillers. Primarily, fibrous panels are made from mineral wool, perlite,cellulosic fibers, fillers and binders.

[0004] Fibrous panel production utilizes combinations of fibers,fillers, bulking agents, binders, water, surfactants and other additivesmixed into a slurry and processed into a fibrous panel. Examples offibers used may include mineral wools, fiberglass, and cellulosicmaterial. Mineral wool is a lightweight, vitreous, silica-based materialspun into a fibrous structure similar to fiberglass. Cellulosic materialis typically in the form of newsprint. Added fillers may includeexpanded perlite, brighteners, such as titanium oxide, and clay.Expanded perlite reduces material density and clay enhances fireresistance. Examples of binders used in fibrous panels include starch,latex and reconstituted paper products which link together and create abinding system locking all ingredients into a structural matrix.

[0005] Organic binders, such as starch, are often the primary componentproviding structural adhesion for the fibrous panel. Starch is often thepreferred organic binder because it is relatively inexpensive. Forexample, fibrous panels containing newsprint, mineral wool and perlitecan be bound together by starch. Starch imparts both strength anddurability to the fibrous panel structure, but is susceptible tomoisture and sag.

[0006] Synthetic polymeric materials such as styrene-acrylate latticesand polyethylene terepthalate mono-filament fibers have been used tobind mineral fiber-based articles together in an effort to overcome thedeficiencies of organic binders. For example, one current methodprovides for disposing a surface charge of styrene-acrylate latticesonto cellulosic components of a mineral fiber panel during the wetformation process with subsequent drying serving to coalesce the latexand bind the fibers and particulates. The use of such moistureinsensitive binders provides for a more dimensionally stable and sagresistant panel. A further example includes attaching polymeric fibersand melted fiber particulates onto fiberglass by directing a stream ofmono-filament high weight polymeric fibers into a hot stream of newlyformed fiberglass, collecting the polymer treated fibers, and thenheat-forming into an article.

[0007] Fibrous acoustical panels formed from mineral fiber areinflexible and cannot be molded into curved or irregular shapes.Furthermore, embossing such boards is only accomplished with greatdifficulty using processes that are destructive and which reduceporosity and destroy the acoustical performance. Such panels are oftenbound with starch and have a high density of about 12-16 lb/ft³. Theformed panels break readily and do not absorb impact energy. They areeasily dented, particularly those with densities low enough to possesshigh acoustical absorption characteristics. Maximum noise reductioncoefficients, NRC values, are approximately 0.75. Thin panels of suchcompositions must necessarily have less porosity to be strong enough fortransporting, handling and installation. These thin panels have evenpoorer acoustical absorption characteristics, with NRC values in therange of 0.45-0.55.

[0008] The other major category of acoustical fibrous panels includespanels made from fiberglass bound with a phenolic resin. Fiberglass is arelatively long continuous fiber compared to rock or slag mineral wools.Fiberglass panels have significantly greater acoustical absorptioncharacter than current mineral fiber products. Fiberglass panels areinflexible because the thermoset binder cannot be post-formed. Thepanels are yellow and have irregular surfaces and densityinhomogeneities. An expensive scrim coat and paint are required to hidethe yellow color, while also allowing acoustical permeation. Further,the phenolic resins traditionally employed to bind fiberglass batts haveassociated environmental problems. The resins deposit on processequipment, requiring frequent shut-downs and cleaning of the equipment.Formaldehyde gas is evolved as the resin cures.

[0009] Thus, a flexible acoustical panel that can be molded and embossedand that is highly acoustically absorbent and possesses a smoothpaintable surface is desirable. Additionally, it would be desirable ifthe panel could be made thin, yet relatively durable and possessing ahigh NRC value. Furthermore, a panel that is not moisture sensitive andrequires no coating or back-coating systems to prevent the panel fromsagging in a humid environment also would be desirable.

SUMMARY

[0010] The present invention provides both a composition and method forforming a thermo-formable acoustical panel. The panel may be formed frommulti-component polymer fibers or mono-filament polymer fibers dispersedin a mineral fiber batt. The polymer fibers are bound to the mineralfibers by the application of heat.

[0011] In greater detail, the acoustical panel includes multi-componentpolymer fibers having a sheath layer which substantially surrounds aninner core. The sheath layer comprises a first polymer exhibiting amelting point which is less than the melting point of a second polymercomprising the inner core. Additionally, the acoustical panel iscomprised of mineral fibers or mineral wool. The acoustical panel alsomay include cellulose and perlite and be coated with an organic coatingor a scrim. The acoustical panel typically has a density of betweenabout 5 lb/ft³ to about 20 lb/ft³ and an NRC value of at least 0.65.

[0012] The method of forming an acoustical panel includes the step ofproviding multi-component polymer fibers having a sheath layersurrounding an inner core. The sheath layer is comprised of a firstpolymer exhibiting a melting point lower than a melting point of asecond polymer comprising the inner core. The provided polymers are thenmixed with mineral fibers to form a fibrous batt. The fibrous batt isthen heated to melt the sheath polymer layer to bind the polymer fibersto the mineral fibers of the fibrous batt to form the acoustical panel.The fibers may be either mixed and dispersed in a high velocity airstream or combined with water to form a wet mixture which is thendewatered to form a fibrous batt. The fibrous batt may be consolidatedto add strength to the acoustical panel. The panel may be consolidatedby sequential heating and cooling and pressing the formed acousticalpanel.

[0013] A further embodiment includes a method of forming the acousticalpanel comprising the steps of providing mono-filament polymer fiberswhich are dispersed and mixed with mineral fibers in an aqueous mix toform a wet fibrous batt. The wet fibrous batt is then dewatered andheated to bond the polymer fibers to the mineral fibers by melting thepolymer fibers.

[0014] An additional method of forming an acoustical panel comprises thesteps of providing dispersible polymer particulate binders which aredispersed and mixed with mineral fibers in a high velocity air stream toform a fibrous batt. The batt is then heated and the particulate bindersare then melted to bond the fibrous batt to form the acoustical panel.

[0015] A further embodiment includes a method of forming an acousticalpanel including the steps of providing dispersible polymer particulatebinders having a glass transition temperature of between about −50° C.to about 75° C. and dispersing and mixing the particulate binders withmineral wool fibers in an aqueous mix to form a wet fibrous batt. Thewet fibrous batt is then dewatered to form a dewatered batt which isthen heated to melt the particulate binders within the dewatered batt toform the acoustical panel.

[0016] An additional embodiment includes a multi-layered acousticalpanel comprising at least a first and second layer. The first layerincludes multi-component polymer fibers having a sheath layersubstantially surrounding an inner core. The sheath layer is comprisedof a first polymer having a melting point lower than a melting point ofa second polymer comprising the inner core and mineral fiber. The secondlayer is in contact with the first layer and the second layer whichincludes both a binder and filler.

[0017] A further embodiment includes a method of forming an acousticalpanel comprising a first mono-filament polymer fiber and a secondmono-filament polymer fiber. The first polymer fiber has a melting pointwhich is lower than the melting point of the second polymer fiber. Thecombined first and second fibers are then dispersed and mixed withmineral wool fibers in an aqueous mix to form a wet fibrous batt. Thewet fibrous batt is dewatered and heated. Upon heating, the firstpolymer fiber substantially melts and binds the fibers together to aidin forming the acoustical panel.

[0018] In an additional embodiment, a method of forming an acousticalpanel comprises providing both dispersible polymer particulate bindersand polymer fibers and dispersing and mixing them with mineral wool toform a fibrous mix. The fibrous mix is then combined to form a fibrousbatt which is heated to substantially melt the particulate binderswithin the fibrous batt to form the acoustical panel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In the drawings:

[0020]FIG. 1 is a schematic view of the multi-component polymer fiberillustrating the outer sheath surrounding the inner core;

[0021]FIG. 2 is a schematic cross-sectional view of a mineral batthaving the multi-component polymer fibers interspersed within themineral wool;

[0022]FIG. 3 is a schematic cross-sectional view of the heated fibrousbatt having a melted polymer sheath layer which has flowed into the woolfiber matrix; and

[0023]FIG. 4 represents a compressed and consolidated finishedacoustical panel.

DETAILED DESCRIPTION

[0024] The present invention provides both a composition and method forforming a thermo-formable acoustical panel. The panel may be formed frommulti-component polymer fibers or mono-filament polymer fibers dispersedin a mineral fiber batt. The polymer fibers are bound to the mineralfibers by the application of heat. The panel exhibits both enhancedthermal insulative properties and fire resistance.

Multi-component Polymer

[0025] In greater detail, the multi-component polymer fiber typicallycomprises at least two polymers. A bicomponent polymer fiber 6 typicallyconsists of a sheath layer 2 which substantially surrounds an inner core4. The sheath layer 2 substantially encases the inner core 4. The sheathlayer 2 is not required to totally surround or encase the inner core 4.The sheath layer 2 is comprised of a polymer having a lower meltingpoint than the inner core 4. The difference in the melting point is suchthat upon the application of heat the sheath layer 2 softens or meltsand bonds with the surrounding fibers which are typically mineralfibers. The inner core 4 preferably remains substantially intact orunmelted such that the inner core 4 fiber provides a fibrous support forthe panel.

[0026] The multi-component panel may be either dry formed or wet formed.The method of forming the panel includes dispersing and mixing thepolymer fibers with mineral wool fibers to form a fibrous batt 8 andheating the fibrous batt 8 to melt the sheath polymer layer to form theacoustical panel. In the dry forming process the mineral fibers aremixed and dispersed in a high velocity air stream. In the wet formingprocess the polymer fibers and mineral fibers are mixed with water toform a wet mixture and then dewatered to form the fibrous batt 8.

[0027] In the step of heating the fibrous batt 8, the batt is heated toa temperature above the melting temperature of the first polymer andbelow the melting temperature of the second polymer. The method mayfurther comprise consolidating the formed acoustical panel by sequentialheating and cooling. The panel may be further processed by pressing theformed acoustical panel into either a flat or curved shape.

[0028] The acoustical panel commonly comprises mineral fibers or mineralwool. Mineral wool may comprise fibers of rock wool or basalt wool. Thefibers, in general, have a diameter of about 3 to about 6 microns.Further, the fibers may be used in the “sized” or “naked” state. Sizingagents such as mineral oils or acrylic polymer dispersions may beemployed. These fibers contribute to the structural integrity andstrength of the panel.

[0029] To provide additional strength and sag resistance, the panel canfurther comprise cellulose fibers derived from wood fibers, primarypaper fibers, secondary paper fibers, or cotton linters. Such primaryand secondary paper fibers respectively include pre- and post-consumerpaper products, such as newsprint paper. The fiber length can be up toabout ¼ inch in length or greater. In one embodiment, the cellulosicfibers are newsprint fibers, which generally have a length of from about¼ millimeter to about 5 millimeters with an average length of about 1millimeter. Specifically, the newsprint comprises cellulosic fibers thatcontribute to the wet strength of the board as it is converted from theslurry to a substantially solid wet felt enroute to becoming the panelin the wet forming process.

[0030] Retention agents may be utilized in wet forming process to assistin retaining the base binder, non-fibrous fillers, and fibers thereinduring de-watering operations. There are many such retention agentsavailable on the market which can be employed in the present invention.One such retention agent is a cationic polyacrylamide marketed asPURACHEM 240 EC by Hercules Chemical Co.

[0031] Non-fibrous fillers may be employed in the panel in an amountfrom 0 to about 20 dry wt. %. The non-fibrous fillers can be selectedfrom kaolin clay, calcium carbonate, silica, vermiculite, ball clay orbentonite, talc, mica, gypsum, and combinations thereof.

[0032] Expanded perlite can also be employed in the panel in an amountfrom 0 to about 30 dry wt. %. Perlite is a volcanic glass ore, similarto obsidian with the capacity to expand greatly on heating, typicallycomprising silica, aluminum, calcium or other alkaline earth silicate.Perlite contributes to the bulk and hardness of the panel. Expandedperlite and a methods of making expanded perlite are discussed in U.S.Pat. No. 5,911,818, which is incorporated herein by reference.Generally, perlite contains 65-75% SiO₂, 10-20% Al₂O₃, 2-5% H₂O, andsmaller amounts of soda, potash, and lime. Expanded perlite denotes anyglass rock and more particularly a volcanic glass that has been expandedsuddenly or “popped” while being heated rapidly. This “popping”generally occurs when the grains of crushed perlite are heated to thetemperatures of incipient fusion. The water contained in the particlesis converted into steam and the crushed particles expand to form light,fluffy, cellular particles. Volume increases of the particles of atleast ten fold are common. Expanded perlite is generally characterizedby a system of concentric, spheroidal cracks, which are called perlitestructure. Different types of perlite are characterized by variations inthe composition of the glass affecting properties such as softeningpoint, type, and degree of expansion, size of the bubbles and wallthickness between them, and porosity of the product.

[0033] To provide fire-retardancy, the panel may include colemanite orboric acid. Boric acid may also be added to assists the panel inresisting color degradation during welt felt drying operations. Othersuch flame-proofing agents may be employed. Furthermore, pigments and/orwater repellants may be employed.

[0034] Additional water and “dry broke” may be added. The “dry broke” ispredominately recycled board material that may have been rejected or cutfrom the commercially acceptable boards, as well as other wasteproducts.

[0035] Additional additives, such as dispersants, defoaming agents,fungicides, and combinations thereof, may be added in the formation ofthe panel.

[0036] In further detail, FIG. 1 depicts the bicomponent polymer fiber6. Example polymer fibers include those available from KoSa, (formerlyHoechst), and the FIT Co. The inner core 4 of such fibers, are mostoften polyester and particularly PET, (polyethylene terepthalate) with amelting temperature of about 280° C. The outer sheath is most often alower melting polyester, perhaps a copolymerized PET derivative, such asPET-g, or a polyolefin, such as polypropylene or polyethylene.

[0037] In FIG. 2 illustrates a cross-sectional view of a mineral woolbatt 8 in which the bicomponent polymeric fibers 6 are interspersed. Themineral wool is represented by the short, fine lines and the bicomponentfibers are represented by the large multi-layered tubes. Whenincorporated into a mineral fiber batt, even in low percentages, themacroscopic bicomponent fibers provide a loft and a continuous structurewithin a relatively low density, highly open batt structure. The formingof such a batt may be accomplished in a variety of ways.

[0038] An air-forming process may be used, in which the fibers arecarried and co-mingled in an air-stream and subsequently deposited on anair-permeable wire conveyer. However, it is preferred that the fiberdispersion and co-mingling processes are not destructive to the mineralfiber. An example air-forming process includes that designed by DOAGmbH, in which the fibers are dispersed and mixed in a high velocityair-stream.

[0039] In the wet-forming method such as in the papermaking process inwhich the fibers are dispersed and co-mingled in water and subsequentlydeposited and dewatered, a wire conveyor may be used.

[0040]FIG. 3 depicts the fibrous batt 8 heated above the melting pointof the sheath polymer but below the melting point of the inner corepolymer. The heating process follows the forming process. Heat isapplied to the batt to provide a temperature in excess of the meltingtemperature of the bicomponent sheath. The sheath polymer layer meltsand flows out into the fiber matrix and binds the mineral wool fibers toone another and to the core polymer fiber that has remained intact as astructural element of the panel. The loft and continuity of the batt isretained and the fibers are bonded together.

[0041] The resulting panel after the step of consolidation is depictedin FIG. 4. In the consolidation step, the bonded batt may be subjectedto a sequential hot and cold plattened pressing. This serves toconsolidate the batt further, while smoothing and compressing a porousskin layer 10 onto both sides of the finished panel. The hot stage ofthe pressing re-melts the binder while compressing and smoothing thesurfaces. The cold stage re-solidifies the binder and sets the panelstructure into place.

[0042] Furthermore, the formed acoustical panel may be further embossedwith a pattern or design and/or molded into a desired shape or form. Theterm “thermo-formed” is used to describe all such processes where theformed acoustical panel is further processed by the application of heatand/or pressure to either emboss the panel or form it into variousshapes or dimensions.

Wet Formed without Consolidation

[0043] A sufficiently rigid and self-supporting panel may be formedwithout the consolidation step when the panel is wet formed. Support forthe wet formed panel may be created by adding several percentages ofpulped newsprint fiber. Pulped newsprint fiber may be used to impartrigidity and process wet-web strength in combination with very lowbicomponent binder fibers. Additionally, natural fiber additions mayalso contribute rigidity and self-support. Examples include pulpedsisal, hemp, abaca or other cellulosic fibers or cut strands of unpulpedfibers in lengths of ¼ inch or longer. Rigid inorganic fibers such asglass, mineral, and carbon may also be used. Chart 1 illustrates exampleformulations for wet-formed structures: CHART 1 Formuala % Batt PhysicalProperties % % Colmanite % Batt Batt Batt Droop Preicted Calonfic FrenchCat- Mineral Newsprint Flame Bicomponent % % Thickness Density MOELength NRC Value Cabin egory Wool Fiber Retardant Binder Fiber PerliteFlocculant (in) (lb/ft3) (PSI) (In) Value (MJ/kg) Results 1 68.93 2.005.00 4.00 20.00 0.07 0.67 8.04 927 12.0 0.87 1.76 M-1 (Q = 0) 2 77.437.00 2.50 3.00 10.00 0.07 0.62 8.64 2973 20.0 0.83 26.51 M-1 (Q = 0)

[0044] The droop length illustrated is the measured horizontal extensionlength of the sample material out from the edge of a support table, atwhich the material deflects or “droops” two inches downward and is arelative measure of the material rigidity. Panels with a 20 inch drooplength will be self-supporting with minimal downward deflection instandard 2′×2′ and 2′×4′ ceiling support grids. The “French Cabin”flamespread test, (NFP 92-50 Epiradiateur test), and the calculatedCalorific Values indicate the materials that will comply with thestringent M-O fire resistance performance for France.

[0045] Acoustical wet formed panels having bicomponent binder fibers canprovide a low density, highly open, acoustically absorbent structure.There is a significant re-bounding expansion of the material in thedrying step of the process, and there is no migration of binder to closethe surface porosity, such as with starch. The combination of newsprintand bicomponent fiber yields even greater wet-web strength and noisereduction coefficient, (NRC), than standard wet-formed mineral fiberproducts. The panels as low as 0.25 lb/ft² basis weight and material ¼inch thick can be successfully processed. The present formed acousticalpanel resists humidity induced sag, and can be made by standardFourdrinier wet-forming techniques. The panels can be heated and formedinto curved, shaped or embossed panels.

Mono-filament Polymeric Fibers

[0046] Mono-filament polymeric fibers may also be added to the fibrousbatt 8 to create the acoustical panels. Panels bound with mono-filamentpolymer fibers such as polypropylene or polyethylene may be successfullywet formed. Mono-filament polymeric fibers such as polypropylene,polyethylene terepthalate and polyethylene can be applied as binders inwet-formed mineral fiber panels to produce a self-supporting, flameresistant, highly acoustical and thermo-formable panel.

Plastic Particulate Binders

[0047] Granulated polypropylene, polyester, and crosslinkablethermoplastic particulates such as the Wacker Vinnex™ core-shell bindersmay be applied as binders in air-formed acoustical ceiling panels. Theparticulates can be dispersed into airlaid webs. The formed batts can bethermally bonded to create highly acoustical soft-fiber panels that canbe post-compressed or surface scrimmed for optimal rigidity andself-support. Additionally, particulates can be dispersed in water,flocculated and retained in wet-formed panels and thermally bonded inthe drying process of the web.

[0048] Furthermore, latexes may be used as a binder. Latexes having alow glass transition temperature, (Tg) such as styrene-butadiene can beapplied as binders. Latexes having Tg range from about −50° C. to about75° C. may be used.

Layered Panels

[0049] Layered panels may be either dry formed or wet formed. In thedry-forming process the layering can be accomplished in several ways.Forming units can be placed in tandem along a conveyor forming screen;such commercially available dry-forming processes as the Danweb, A/S andM&J A/S systems capable of forming layered structures of a variety ofproducts for the disposables and hygienic markets. Acoustical panelsgenerally have greater thickness and basis weight than these products.Mineral fibers have significantly higher density than the organicfibers, fillers and absorbents that comprise the disposables. Otherdry-forming systems based on lickerin roll/vacuum technology, such asthe Laroche S. A and DOA GmbH systems may be used to deliver separatefiber streams to several lickerin-rolls along a conveyed forming screen.Alternatively, preformed non-woven scrims or batts may be unrolled andfed beneath or above a core batt fiber stream and thermally orchemically adhered to each other in a thermal bonding oven.

[0050] Furthermore, wet-forming techniques may be used in separate stockstreams to one of several forming head-boxes along a conveyed formingwire, with the application of vacuum dewatering. An “Oliver” type vacuumdrum or Fourdinier method may be used.

[0051] The multi-layer mineral fiber panel comprises one layer and asecond layer which is co-formed or laminated to the other. Theadditional second layer may be comprised of binder of about 0.2% toabout 15%. The binder may be comprised of bicomponent, low-meltmonofilament binder fiber, a thermoplastic particulate, latex or resinbinder, a thermosetting particulate, latex or resin binder, acombination thermoplastic/thermosetting particulate, latex, resin binderor a combination thereof. The panel may comprise about 85% to about99.8% by weight of the filler. The filler may be glass, syntheticpolymeric, or natural cellulosic fibers or combinations.

[0052] The second layer may be employed as a facing layer to impartsmoothness, homogeneity and surface finish to the product. The secondlayer may also contribute to the rigidity, strength and structural unityof the panel. The second layer may also be employed as a backing layerfor support, strength and sag resistance and as a barrier to preventsound from permeating through the product to increase the CAC (ceilingattenuation class) of the panel. Generally, the facing layer may be lowdensity, permeable, thinner than the first or primary layer, and of auniform formation and visual quality. The backing layer is typicallyimpermeable to air and sound.

[0053] Additional layers may also be added. For example, a facing andbacking may be co-formed or laminated to a core layer. Structures withmore layers are also considered.

Multiple Mono-filament Polymer Fibers

[0054] A further method of forming an acoustical panel comprisingmanufacturing an acoustical panel having at least two mono-filamentpolymer fibers. In an embodiment, a first mono-filament polymer fiberand a second mono-filament polymer fiber are combined in a fibrous mix.The first polymer fiber has a melting point which is lower than themelting point of the second polymer fiber. The lower melting pointpolymer is intended to bind the surrounding fibers by substantiallymelting upon heating. The higher melting point polymer binds as asubstantially unmelted fiber within the fibrous matrix of the panel. Ofcourse, more than two types of polymer fibers may be used. It iscontemplated that multiple polymer fibers having various melting pointsmay be used.

[0055] In one embodiment, first and second fibers are combined and thendispersed and mixed with mineral wool fibers in an aqueous mix to form awet fibrous batt 8. The wet fibrous batt 8 is dewatered and heated. Uponheating, the first polymer fiber substantially melts and binds thefibers together to aid in forming the acoustical panel.

Particulate Binders and Polymer Fibers

[0056] In this embodiment, a method is provided for forming anacoustical panel comprising both a dispersible polymer particulatebinder and a polymer fiber. Of course multiple binders and fibers may becombined in this method. In the method the binders and fibers aredispersed and mixed with mineral wool to form a fibrous mix. The fibrousmix may then be combined to form a fibrous batt 8 which is then heatedto substantially melt the particulate binders within the fibrous batt 8to form the acoustical panel.

Thermal Insulation and Fire Resistance

[0057] The present panel may exhibit a Thermal K insulation value ofbetween about 0.2 to about 0.3 BTU-in/hr-ft²-° F. In a furtherembodiment, the Thermal K insulation value of between about 0.22 toabout 0.3 BTU-in/hr-ft²-° F. The thermal insulation values may bedetermined by the ASTM C 518-91 thermal conductivity test. The fireresistance of the panel can be determined by ASTM E-119 fire resistancetest. The panel may resist flame spread of between about 40 minutes toabout 120 minutes under ASTM-119. In a further embodiment, the panel mayresist flame spread or failure between about 60 minutes to about 100minutes.

EXAMPLES

[0058] The invention will be more easily understood by referring to theexamples of the invention and the control examples that follow. Thefollowing examples are given for illustrative purposes and are not to beunderstood as limiting the present invention.

[0059] The humidity sag test used in the present examples was run in 4cycles. One cycle is 17 hours at 82° F.-90% RH, followed by 6 hours at82° F.-35% RH. Typically, the greatest sag deflection is observed duringthe 4^(th) cycle 90% RH condition.

[0060] The noise reduction coefficient (NCR) is determined by thereverberation room test ASTM C423. It averages the amount of soundabsorption at 4 critical frequencies. Values range from 0.00 to 1.00.

[0061] FSR is a general indication of flame spread performance and thevalues for the FSR test were determined under the ASTME84 tunnel test.

[0062] In the present examples the air-forming system used are designedand manufactured by DOA GmbH in Wels, Austria. In the wet formingexamples, an Armstrong wet-lay Fourdrinier pilot machine was used.Although there was a difference in the required fiber length of thebicomponent for the wet-lay process, and some difference in theformation quality and surface smoothness of the initial batt, bothprocesses yielded adequately formed batts that compressed to smooth,rigid, self-supporting, durable, acoustical panels.

Example 1

[0063] In Example 1, the material was air-formed by the DOA process. Thefinished compression and smoothing of the panel was accomplished on aSchott & Meissner Thermofix plattened hot/cold stage continuouscompression unit. The formulation of the formed acoustical panel islisted below: Material Mass % Source Specifications Mineral Wool 70Armstrong 0.7-1.2 mm length Pontarlier Plant 4-6 micron diameterBicomponent 30 Leigh Fibers Japanese PET/PET Fiber Spartanburg, SC 110°C. sheath melt 4 denier 2 inch length

[0064] Finished panel dimensions, density, and physical properties arelisted below: Deflection at 90% Projected Projected Dimensions SuspendedRH 4th NRC** NRC FSR*** Prototype Density l, w, th. Deflection Cycle*(Imped.) (Imped.) 30—30 Set (lb/ft³) (inches) (inches) (inches) unbackedbacked Tunnel 1 12.2 24, 24, 0.78 (−)0.029 (−)0.061 0.94 0.74 26 2 17.6124, 24, 0.69 (−)0.019 (−)0.051 0.71 0.69 —

[0065] Furthermore, a standard application of paint was applied to theacoustical panels formed in Example 1. The paint was applied to a verytough and durable fiberglass scrim with which the product is faced. Ametal tyne drag test, the “Hess rake” test, is used to measure of thesurface scratch resistance of acoustical panels. The painted prototypematerial Hess rake break through value was 25.

Example 2

[0066] In this Example, the binder level was reduced to form a thinnerpanel. The DOA air-lay process and the Thermofix compression unit wereemployed in this Example. One to two inch flax fibers were incorporatedinto the formulation to provide loft for a reduced density category. Thechart bellow illustrates the tested results. Deflection FormulationDimensions Suspended at 90% RH NRC NRC Wool Density l, w, th. Deflection4th Cycle* Tested Tested Ctgry Bico, Flax (lb/ft³) (inches) (inches)(inches) (unbacked) (backed) 1 90 10 0 21.48 24, 24, 0.215 (−)0.109(−)0.140 — — 2 85 15 0 28.04 24, 24, 0.305 (−)0.116 (−)0.145 — — 3 70 2010 11.34 24, 24, 0.518 (−)0.068 (−)0.082 0.90 0.65 4 80 20 0 30.19 24,24, 0.382 (−)0.052 (−)0.080 0.71 0.45

[0067] Furthermore, an acoustical panel formed in Example 2 was placedover the top of a wire cylinder and heated to 300° F. in a convectionoven. The panel was able to soften and conform to the shape of thecylinder. Upon cooling, the panel set into a tightly curved panel. Nochange in panel thickness was encountered.

Example 3

[0068] Example 3 illustrates forming an acoustical panel by awet-forming process on a Fourdrinier pilot line and then drying andthermally setting in a continuous convection oven. The bicomponent fiberused for this processing was obtained from KoSa Corporation, Charlotte,N.C. This fiber, designated Cellbond 105 is a polyethelene sheathcomposition rather than a low melt PET sheath, and is only /½ inch longrather than 2 inches long. The core is PET. The formulations used inExample 3 are illustrated below: Material Mass % Source SpecificationsMineral Wool 90 MFS, Bethlehem, 0.7-1.2 mm length PA 4-6 micron diameterBicomponent 10 KoSa Fibers Bico PE/PET Fiber Charlotte, NC 128° C.sheath melt 4 denier ½ inch length

[0069] Within this Example the Cellbond 105 dispersed very uniformlywith the mineral wool in water. The dispersion dewatered rapidly on theFourdrinier machine, yielding a reasonably well formed wet-mat that wasadequately smoothed with press-rolls. No flocculant was required toassist in dewatering and a significantly low moisture content of thewet-mat, (42%), was determined. Of course a flocculant may be used. Thedrain-water was clean and fiber/particle free. The wet mats weretransferred onto expanded metal screens for support through the rollerconveyor of the dryer.

[0070] The material was dried in a belted through-convection oven and itset in approximately 30 minutes at 350° F. The resulting batt wasobserved to be significantly lower in density than a bat of similarformulation made by the air-forming process, 5.6 lb/ft³ rather than15-20 lb/ft³. This lower density presumably results from an expansioninduced by the evaporation of water. The batts were compressed intopanels using a static plattened press with top and bottom heated. Thecompressed batts were removed from the press as rapidly as possible anda cool heavy steel plate was put on top of it to avoid rebounding.Densities of 18-19 lb/ft³ were achieved and the resulting panels wererelatively self-supporting and smooth.

Insulation Performance

[0071] A 1.25″ thick thermo-formable acoustical panel was produced onFourdrinier forming equipment of the formulation given below having adensity of 9 lb/ft³. Mineral fiber 84.5% KOSA celbond 105 bicomponentfiber binder 5.0% Newsprint fiber 8.0% Colemanite 2.5%

[0072] Subsequently, the produced material, with no surface finishing,was tested for thermal conductivity using ASTM C 518-91. Matri. MeanThermal k Conductance R Value Thermal Th. Temp (BTU/in/ (BTU/ (l/Con- K(in) Slope (° F.) hr-ft²-F.°) hr-ft²-F.°) ductance) (W/m-°K.) 1.110 075.01 0.2514 0.2265 4.4146 0.0363

[0073] The tested R-value for the thermo-formable acoustical panel at 1″is 4. It is, therefore, comparable in insulation capacity to fiberglassand duct board.

Fire Resistance

[0074] A ½″ and 1″ thick thermo-formable acoustical batt was produced.These materials were finished with a laminated 80 g/m² fiberglass scrimapplied with a flame-retarded adhesive. An acoustical finish paint wasapplied to the scrimmed surface, and a light cosmetic paint coat wasapplied to the back of the finished panel. Mineral fiber 86.5% KOSAcelbond 105 bicomponent fiber binder 3.0% Newsprint fiber 8.0%Colemanite 2.5%

[0075] The materials were tested under ASTM E-119 fire resistance test.This is a gas furnace test designed to simulate a real fire burningbeneath the ceiling material, suspended in fire-resistive ceilingsuspension grid. As the fire test proceeds, the air temperature ismonitored in the plenum above the ceiling, as is the temperature of asteel structural beam in the plenum. The mechanism for failure is eitherexcessive heat transfer through the ceiling, or disintegration anddropout of the ceiling panel. Both the ½″ and 1″ materials were testedas well as an Armstrong Prima European mineral fiber control panel. Thiscontrol material is rated for 60 minutes in the Benelux and Britishmarkets, as tested in European full-scale fire tests. Results: TimeResearch to Test Notebook Entry Failure Failure Test Report (Notebook-Material (Min) Mechanism Date No. page) Prima Control 63.5 Fell-out Feb.15, 2002 T-627346 10613-131 ½″ TF Panel 76 Fell-out Feb. 22, 2002T-627396 10613-132 1″ TF Panel 80 Fell-out Feb. 22, 2002 T-62739610613-132

[0076] While Applicants have set forth embodiments as illustrated anddescribed above, it is recognized that variations may be made withrespect to disclosed embodiments. Therefore, while the invention hasbeen disclosed in various forms only, it will be obvious to thoseskilled in the art that many additions, deletions and modifications canbe made without departing from the spirit and scope of this invention,and no undue limits should be imposed except as set forth in thefollowing claims.

What is claimed is:
 1. An acoustical panel comprising: multi-componentpolymer fibers, each of the polymer fibers having a sheath layersubstantially surrounding an inner core, the sheath layer comprising afirst polymer having a melting point lower than a melting point of asecond polymer comprising the inner core; and mineral wool.
 2. Theacoustical panel of claim 1, wherein the first polymer comprising thesheath layer has a melting point of between about 100° C. to about 200°C.
 3. The acoustical panel of claim 1, wherein the second polymercomprising the inner core has a melting point of at least about 160° C.4. The acoustical panel of claim 1, wherein the first polymer comprisingthe sheath layer is selected from the group consisting of a polyester, apolyethylene, a polyolefin and combinations thereof.
 5. The acousticalpanel of claim 1, wherein the second polymer comprising the inner coreformed from a polymeric material selected from the group consisting of apolyester, polypropylene, and combinations thereof.
 6. The acousticalpanel of claim 5, wherein the polyester is polyethylene terepthalate. 7.The acoustical panel of claim 1, wherein the mineral wool forms a fibercomplex having the multi-component polymer fibers interdispersed withinthe fiber complex.
 8. The acoustical panel of claim 1, wherein the outerlayer is bound to the mineral wool.
 9. The acoustical panel of claim 1,wherein the panel has an NRC value of at least about 0.65.
 10. Theacoustical panel of claim 1, further comprising a cellulosic material.11. The acoustical panel of claim 10, wherein the cellulosic material isselected from the group consisting essentially of newsprint, pulpedsisal, hemp abaca and combinations thereof.
 12. The acoustical panel ofclaim 10, wherein the cellulosic material comprises up to about 40% byweight of the panel.
 13. The acoustical panel of claim 1, furtherincluding a reinforcement fiber having a length between about 0.2 inchesto about 2 inches.
 14. The acoustical panel of claim 1, wherein themulti-component fibers comprise from about 2% to about 40% by weight ofthe panel.
 15. The acoustical panel of claim 1, wherein the mineral woolcomprises from about 60% to 98% by weight of the panel.
 16. Theacoustical panel of claim 1, further having a density of between about 5lb./ft³ to about 40 lb./ft³.
 17. The acoustical panel of claim 16,wherein the density of the panel is between about 5 lb./ft³ to about 10lb./ft³.
 18. The acoustical panel of claim 1, further including anembossed surface.
 19. The acoustical panel of claim 1, furtherexhibiting a humidity sag test deflection at 90% of less than 0.125inches.
 20. The acoustical panel of claim 1, wherein the panel has athermal K value of between about 0.22 to about 0.3 BTU-in/hr-ft²-° F.21. The acoustical panel of claim 1, wherein the panel has fireresistance of between about 40 minutes to about 120 minutes according toASTM E-119.
 22. A method of forming an acoustical panel comprising thesteps of: providing multi-component polymer fibers having a sheath layersurrounding an inner core with the sheath layer being comprised of afirst polymer having a melting point lower than a melting point of asecond polymer comprising the inner core; dispersing and mixing thepolymer fibers with mineral wool fibers to form a fibrous batt; heatingthe fibrous batt; and melting the sheath polymer layer to form theacoustical panel.
 23. The method of claim 22, wherein the polymer fibersand mineral fibers are mixed and dispersed in a high velocity airstream.
 24. The method of claim 22, further comprising mixing anddispersing the polymer fibers and mineral fibers in water to form a wetmixture.
 25. The method of claim 22, further including de-watering thewet mixture to form the fibrous batt.
 26. The method of claim 22,wherein the fibrous batt is heated to a temperature above the meltingtemperature of the first polymer and below the melting temperature ofthe second polymer.
 27. The method of claim 22, further comprisingconsolidating the formed acoustical panel.
 28. The method of claim 27,wherein the formed acoustical panel is consolidated by sequentialheating and cooling.
 29. The method of claim 28, further comprisingpressing the formed acoustical panel.
 30. The method of claim 22,wherein the formed acoustical panel is form cured.
 31. The method ofclaim 22, wherein the panel has a thermal K value of between about 0.22to about 0.3 BTU-in/hr-ft²-° F.
 32. The method of claim 22, wherein thepanel has a fire resistance of between about 40 minutes to about 120minutes according to ASTM E-119.
 33. A method of forming an acousticalpanel comprising the steps of: providing mono-filament polymer fibers;dispersing and mixing the polymer fibers with mineral wool fibers in anaqueous mix to form a wet fibrous batt; dewatering the wet fibrous battto form a dewatered batt; heating the dewatered batt; and melting thepolymer fibers within the dewatered batt to form the acoustical panel.34. The method of claim 33, wherein the mono-filament polymer fibers areselected from fibers consisting of polypropylene, polyethyleneterepthalate, polyethylene and combinations thereof.
 35. The method ofclaim 33, wherein the panel has a thermal K value of between about 0.22to about 0.3 BTU-in/hr-ft²-° F.
 36. The method of claim 33, wherein thepanel has a fire resistance of between about 40 minutes to about 120minutes according to ASTM E-119.
 37. A method of forming an acousticalpanel comprising the steps of: providing dispersible polymer particulatebinders; dispersing and mixing the particulate binders with mineral woolfibers in a high velocity air stream to form a fibrous batt; heating thefibrous batt; and melting the particulate binders within the fibrousbatt to form the acoustical panel.
 38. The method of claim 37, whereinthe particulate binders are selected from the group consisting ofpolypropylene, polyesters, cross linkable thermoplastics andcombinations thereof.
 39. The method of claim 37, further comprisingconsolidating the formed acoustical panel.
 40. The method of claim 37,wherein the formed acoustical panel is consolidated by sequentialheating and cooling.
 41. The method of claim 37, further comprisingpressing the formed acoustical panel.
 42. The method of claim 37,further including surface scrimming the formed acoustical panel.
 43. Themethod of claim 37, wherein the panel has a thermal K value of betweenabout 0.22 to about 0.3 BTU-in/hr-ft²-° F.
 44. The method of claim 37,wherein the panel has a fire resistance of between about 40 minutes toabout 120 minutes according to ASTM E-119.
 45. A method of forming anacoustical panel comprising the steps of: providing dispersible polymerparticulate binders having a glass transition temperature of betweenabout −50° C. to about 75° C.; dispersing and mixing the particulatebinders with mineral wool fibers in an aqueous mix to form a wet fibrousbatt; dewatering the wet fibrous batt to form a dewatered batt; heatingthe dewatered batt; melting the particulate binders within the dewateredbatt to form the acoustical panel; and thermo-forming the acousticalpanel.
 46. The method of claim 45, further including applying a scrimcoat to the thermo-formed acoustical panel.
 47. The method of claim 45,further including applying an organic coating to the thermo-formedacoustical panel.
 48. An acoustical panel comprising: a first layerincluding multi-component polymer fibers, the polymer fibers having asheath layer substantially surrounding an inner core, the sheath layercomprising a first polymer having a melting point lower than a meltingpoint of a second polymer comprising the inner core and mineral wool;and a second layer in contact with the first layer and the second layerincluding a binder and filler.
 49. The acoustical panel of claim 48,wherein the binder is selected from the group consisting ofmulti-component polymer fibers, monocomponent polymer fibers,thermoplastic particulate, latexes, resins, thermosetting particulatesand combinations thereof.
 50. The acoustical panel of claim 48, whereinthe filler is selected from the group consisting of glass, polymericmaterials, cellulose and combinations thereof.
 51. The acoustical panelof claim 48, wherein the acoustical panel comprises between about 0.2%to about 20% by weight binder and about 80% to about 99.8% by weightfiller.
 52. The acoustical panel of claim 48, wherein the panel has athermal K value of between about 0.22 to about 0.3 BTU-in/hr-ft²-° F.53. The acoustical panel of claim 48, wherein the panel has a fireresistance of between about 40 minutes to about 120 minutes according toASTM E-119.
 54. A method of forming an acoustical panel comprising thesteps of: providing a first mono-filament polymer fiber and a secondmono-filament polymer fiber, wherein the melting point of the firstpolymer fiber is lower than the melting point of the second polymerfiber; dispersing and mixing the first and second polymer fibers withmineral wool fibers in an aqueous mix to form a wet fibrous batt;dewatering the wet fibrous batt to form a dewatered batt; heating thedewatered batt; and substantially melting the first polymer fiber withinthe dewatered batt to form the acoustical panel.
 55. The method of claim54, wherein first polymer fiber has a melting point of between about100° C. to about 200° C.
 56. The method of claim 54, wherein the secondpolymer fiber has a melting point of at least about 160° C.
 57. Themethod of claim 54, wherein the first polymer fiber comprises a materialselected from the group consisting of a polyester, a polyethylene, apolyolefin and combinations thereof.
 58. The method of claim 54, whereinthe second polymer fiber comprises a material selected from the groupconsisting of a polyester, polypropylene, and combinations thereof. 59.The method of claim 54, wherein the panel has a thermal K value ofbetween about 0.22 to about 0.3 BTU-in/hr-ft²-° F.
 60. The method ofclaim 54, wherein the panel has fire resistance of between about 40minutes to about 120 minutes according to ASTM E-119.
 61. A method offorming an acoustical panel comprising the steps of: providingdispersible polymer particulate binders and polymer fibers; dispersingand mixing the particulate binders and polymer fibers with mineral woolto form a fibrous mix; combining the fibrous mix to form a fibrous batt;heating the fibrous batt; and substantially melting the particulatebinders within the fibrous batt to form the acoustical panel.
 62. Themethod of claim 61, wherein the particulate binders, polymer fibers andmineral wool fibers are mixed in a high velocity air stream.
 63. Themethod of claim 61, further including adding water to the fibrous mix.64. The method of claim 61, wherein the panel has a thermal K value ofbetween about 0.22 to about 0.3 BTU-in/hr-ft²-° F.
 65. The method ofclaim 61, wherein the panel has fire resistance of between about 40minutes to about 120 minutes according to ASTM E-119.